I shoot quite often. If you learn to shoot with your left right shut you will need to calibrate your sight to shoot for something I know as a 'counter-paralax'. When i say "left eye" that might be your right eye, it depends on how you shoot. You cannot calibrate a sight properly without choosing left, right, or having both eyes open...

Both eyes are preferred for a killer, because you want to have awareness. But it is not an easy way to shoot, or train, or learn.

On another note, I had a cal .22 blow on my face once, on a perfectly tuned rifle, and the reason I kept my eye, is because the exit is on the right hand side. Most rifles are build like that.